When the cruise ended hours later, the mayoral campaign of state Representative Martin J. Walsh was there, handing seniors goodie bags, which included a sugar cookie.

“Candidates are everywhere I go,” said Sheba Barboza, 77, of Hyde Park, sitting on the ship.

Here is a well-known political truism: Seniors are a captive audience, and they vote. In this election, with 12 candidates running for mayor, seniors are getting attention as never before. Forget trying to land a table at Rino’s restaurant in East Boston. Time at a senior center may be one of the hardest reservations to secure this September.

“Every year they come by, but this year [the mayor’s race] is overwhelming,” said Judy Leary of Metro Management, who handles candidate visits with senior citizens at five housing complexes in East Boston and the North End. “They like it when people bring food.”

Candidates come bearing pizza, doughnuts, ice cream, and cookies. They show up at coffee hours and concerts. Arroyo played dominoes with older voters in Hyde Park. Walsh gave away $5 CVS gift cards at a senior center on Dorchester Avenue as part of a raffle, which included translators reading winning numbers in Vietnamese and Cape Verdean Creole.

Another candidate, Councilor Michael P. Ross, served as bingo master at one event and, at another, brought along paramedics to provide free health screenings. He inadvertently sparked a ruckus at a senior center in Dorchester with his take-a-snapshot-with-the-next-mayor promotion.

Voters age 65 and older cast roughly 27 percent of ballots in the last preliminary mayoral election, in 2009. Compare that with the 35-and-under crowd, which represented just 15 percent of the electorate. There’s a reason candidates are packing their public schedules with senior centers, not nightclubs.

“Above any other demographic, seniors are going to go out and vote,” said John M. Tobin Jr., a former city councilor. “It’s generational. A lot of these seniors learned how to vote coming out the womb. It’s instilled in them.”

Campaign outreach to seniors has been aggressive, creative, and well documented. Visits with older voters are often photographed and promoted on Twitter with saccharine messages that end in exclamation points.

“With my good friend Cassy and hundreds of seniors at a great concert in Boston!!” wrote Councilor Rob Consalvo via Twitter on July 24.

Walsh struck a similar note Monday: “Thank you to the many Seniors who came out!”

Kayana Szymczak for the Boston Globe

Daniel F. Conley greeted senior citizens.

One of the most popular stops on the senior circuit has been Sant Belvi, also known as the Haitian Adult Day Health Center in Dorchester. Mayoral hopeful John F. Barros tweeted about his stop there Aug. 13.

“Talking with Haitian seniors at Sant Belvi! Lots of energy and spirit!”

Golar Richie visited Aug. 22 and tweeted a thank you in Haitian Creole. “Mesi anpil to seniors at Sant Belvi Haitian Adult Day Health Center for such a warm welcome!”

It was Ross, however, who may have had the most memorable visit to Sant Belvi. He revived a gimmick from his first run for City Council in 1999, when he used a Polaroid instant camera to take snapshots of himself with seniors, which he gave as a keepsake. The pictures are mounted in paper frames that include emergency phone numbers and a reminder to vote for Ross.

Ross staff members initially snickered, but the instant photographs have been a hit. The councilor tells audiences it is their chance to be in a snapshot with the next mayor. At Sant Belvi, so many people wanted photos that it got out of hand. Ross’s staff tweeted an image of the candidate surrounded by older Haitian women who had become impatient and were jockeying for their turn with the candidate.

“They had to call security because there was a fracas,” Ross said.

Earlier this week, Ross had his camera at the Lyman School Apartments, a housing complex for seniors in East Boston.

“I like this guy,” said Lorraine Caldarelli, 60, who beamed as she posed for a snapshot with Ross. “This is a great idea. I’ll remember his face. The other ones come and go.”

Kayana Szymczak for the Boston Globe

Charlotte Golar Richie spoke with Rita Dixon (right) and Florence Wright as they sat down for lunch.

But the cruise was the real bonanza. Organized each year by Boston police, the cruise on the Spirit of Boston drew 565 people, the majority seniors.

“Seniors have a long history and tradition of voting,” Conley said. “When there is such a large group of seniors, you really want to take the opportunity.”

Arroyo arrived first and claimed prime position at the foot of the gangway, acting almost as a greeter as seniors climbed aboard.

“I’ve stood on this spot every year I’ve been on the City Council,” Arroyo said after hugging a woman named Thelma. “Boston voters want to get to know you before they vote for you. That’s especially true of seniors.”